Equipment: Vermeer® 24x40SII; StraightLine® 4″ Air Hammer System; Ingersoll Rand 1150 cfm x 350 psi portable air compressor
The Challenge: Trawick encountered a bore in North Little Rock, Arkansas that was 310 foot in length. The ground condition presented a challenge due to the ever changing sub surface conditions, ranging from clay, gravel, limestone, shale, and sandstone. The bore was 310 feet long in a congested utility easement; several attempts had been made on this project to complete these bores with conventional HDD methods, with little to no success. At this point Trawick contacted StraightLine to explore the RockEye air hammer system. Ron Becker StraightLine’s lead air hammer field technician was deployed to demonstrate the systems capabilities.
The StraightLine® 4″ RockEye Air Hammer System entered the ground at minus 20% slope in fractured shale and fill. At approximately 4-feet of depth a harder shale and limestone was encountered. The bore was leveled out to clear the existing power and communications cables. At several points along the 310-foot bore the air hammer worked through the harder grey-black shale with ease. Approximately 30 feet from the receiving pit the air hammer was gradually steered up entering the tie-in point at approximately 30″ deep.
Outcome: The StraightLine® RockEye Air Hammer System easily handled all formations. The bore path for the dual 2″ conduits ran a near perfect running line throughout the bore. The gas and power lines had been exposed and the hammer negotiated the bore path with precision, hitting the connecting pit dead on.